A mass of \(5~\text {kg}\) is moving along a circular path of radius \(1~\text {m}\). If the mas moves with \(300~\text {rev/min}\), its kinetic energy would be
1. \(250 \pi^2~\text{J}\)
2. \(100 \pi^2~\text{J}\)
3. \(5 \pi^2~\text{J}\)
4. \(0\)
1. | 2. | ||
3. | 4. |
A man of mass \(m,\) standing at the bottom of the staircase, of height \(L,\) climbs it and stands at its top.
(a) | work done by all forces on man is equal to the rise in potential energy \(mgL.\) |
(b) | work done by all forces on man is zero. |
(c) | work done by the gravitational force on man is \(mgL.\) |
(d) | the reaction force from a step does no work because the point of the application of the force does not move while the force exists. |
Choose the correct option:
1. (a), (d)
2. (a), (c)
3. (b), (d)
4. (a), (b), (c)
1. | same as the same force law is involved in the two experiments. |
2. | less for the case of a position, as the position moves away more rapidly and the force on it weakens. |
3. | more for the case of a position, as the position moves away from a larger distance. |
4. | same as the work done by charged particle on the stationary proton. |
A man squatting on the ground gets straight up and stands. The force of reaction of the ground on the man during the process is
1. | constant and equal to mg in magnitude. |
2. | constant and greater than mg in magnitude. |
3. | variable but always greater than mg. |
4. | at first, greater than mg and later becomes equal to mg. |